The present invention relates to a recording apparatus and, more particularly, to a laser printer.
FIG. 1 shows a conventional laser printer. Reference numeral 2 denotes a housing. Located at the lower portion of housing 2 is cassette 4 which holds sheets of paper P. Paper P is extracted from cassette 4 by paper-supply roller 6, and is conveyed via guide 8 to a pair of register rollers 10 where it is positioned in preparation for image formation. Paper P is then fed between photosensitive drum 12 and transfer charger 14. Photosensitive drum 12 carries thereon a toner image formed by exposure means 16, developing means 18, etc. The toner image is transferred to paper P by transfer charger 14. After the transfer of the toner image, paper P is conveyed via guide 20 to image-fixing means 22, which includes heat roller 24 and press roller 26. Image-fixing means 22 fixes the toner image on paper P. Thereafter, paper P is conveyed by a pair of exit rollers 28 to an external tray, not shown.
Housing 2 comprises upper unit 30 and lower unit 32. Upper unit 30 is pivotally movable about shaft 34, whereby housing 2 can be opened and closed as required.
Image-fixing means 22 includes cover 36 surrounding heat roller 24 and press roller 26. Cover 36 is secured to lower unit 32.
Press roller 26 can be brought into contact with or set apart from heat roller 24 by the operation of arm 38. More specifically, as upper unit 30 is opened, arm 38, which is urged by spring 40, turns clockwise. Hence press roller 26 moves away from heat roller 24. As upper unit 30 is closed, arm 38 is pushed downward by cover 42 of exit roller 28. As a result, arm 38 turns counterclockwise, and press roller 26 is pressed against heat roller 24.
In the conventional apparatus, cover 36 of image-fixing means 22 is secured to lower unit 32 of housing 2, as described above. With this structure, in order to replace heat roller 24 or press roller 26 with a new one, numerous parts arranged near roller 24 or 26 must be detached from the housing, making the replacement very troublesome, time consuming and expensive.